The present invention relates to cable construction but in particular to optical waveguide cable construction, the optical waveguides being formed of glass or similar fibers.
Optical waveguides are a relatively new development and no significant commercial use has taken place to date. In view of this, optical waveguide cable construction is a new art. Some of the problems encountered in optical waveguide cable construction are set out in the following. To provide useful optical waveguides, signal attenuation must be maintained low and preferably below about 10 db/kilometer. Optical waveguides transmit visible or invisible light. In transmission, such light signals are readily attenuated in response to relatively small distortions of the optical waveguide. For example, relatively sharp bends, or a rough adjacent surface may produce sufficient distortion within the optical waveguide to result in totally unacceptable signal attenuation. Similarly, transverse or longitudinal stresses imposed upon the optical waveguide fibers during cable manufacture or inherent in the resulting structure may produce totally unacceptable signal attenuation in the resulting cable. These and many other problems have been encountered in producing an acceptable optical waveguide cable. In view of this, prior art cable manufacture, that is manufacture of metallic or the like cables, has been found to be unacceptable.
For a better understanding of optical waveguide fibers and their manufacture, reference is made to the following U.S. patents: U.S. Pat. No. 3,659,915 issued to R. D. Maurer and P. C. Schultz; U.S. Pat. No. 3,711,262 issued to D. B. Keck and P. C. Schultz; U.S. Pat. No. 3,737,292 issued to D. B. Keck, P. C. Schultz and F. Zimar; U.S. Pat. No. 3,775,075 issued to D. B. Keck and R. D. Maurer; and U.S. Pat. No. 3,823,995 issued to L. L. Carpenter.